In preboot mode you should be able to reload the same version.
You need to get a "known" good GUPDATE.GCD for your device.
Use this to make cure using Garmincure3.
Once GarminCure3 is successfully loaded do not disconnect device from usb it should reboot in flash drive mode.
You need to get into the filesystem in order to delete the map file that your friend copied to your device. You also need to delete the GUPDATE.GCD file in the device.
Next you need to make Original firmware with Garmincure3 and reflash.
I don't know if Garmincure3 has been tested on 2495.
Maybe someone can confirm.
Make sure that your garmin drivers are up to date.
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